# Marlon Dumas @ BPMN 2010

### Transcript

Unraveling Unstructured Process Models

Marlon Dumas

University of Tartu, Estonia

Joint work with Artem Polyvyanyy and Luciano García-Bañuelos

Invited Talk, BPMN’2010 Workshop, Potsdam, 14 Oct. 2010

Poll: Which desk do you

prefer?

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Poll: Which model do you prefer?

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The Problem

• Premise: Structured is “better”

– Easier to understand

– Easier to analyze

– Easier to automatically layout

– Easier to abstract (zoom-out)

• We know not all models can be structured…

• Which ones can, which ones can’t?

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Analysis of Structured Models

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CTparallel = Max{T1, T2,…, TM}

CT = p1T1+p2T2+…+pmTm=

CT = T/(1-r)

CT = T1+T2+…+ Tm

Laguna & Marklund (2005): Business Process Modeling, Simulation and Design

Automated Layout and Abstraction

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Wil van der Aalst et al., Process Mining Tutorial

A Bit of History

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1968 1969 1970s (and 80s)

20 years (and 200 papers) later…

• Everything can be structured if you accept to

break and continue

• Everyone forgot to release their implementation

(they were ashamed since it was full of GOTOs)

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40 years (and 400 papers) later

• We can structure any BPMN

diagram, except:

– “Incorrect” ones

– Cycles with multiple exit points

– Z-structures

– Inclusive join gateways, complex

gateways and other demons

• Try it out: http://sep.cs.ut.ee/Main/bpstruct

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Corollary (if you care)

• Any (sound) BPMN model can be

transformed into an equivalent (readable)

BPEL process definition

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• If BPEL had break/continue statements or we use boolean variables to simulate break/continue statememts

• And the BPMN model does not have inclusive join gateways, complex gateways and other demons

• And some other minor details not worth mentioning

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Behavioral Equivalence

Preserves the level of concurrency in

a process model

Sequential simulation of a

process model

Fully concurrent

bisimilar (FCB)

Weakly

bisimilar

Weakly

bisimilar

Sequential simulation of a

process model

Starting Point – Process

Structure Tree

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Johnson et al. (PLDI’1994), Vanhatalo et al. (BPM’2008)

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Taxonomy of Process Fragments

■ Trivials, polygons, and bonds are structured fragments

■ Rigids are “unstructured”

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Homogeneous XOR Rigid

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Homogeneous AND Rigid

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Block-structured version…

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Homogeneous AND Rigid that

cannot be structured

• Causal rules:

– {A, B} { C }

– { B } { D }

• Overlap on the left-hand side of the rules

Compare to this…

• Causal relations

– {A, B} {C, D}

Heterogeneous Acyclic Rigid

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Equivalent Structured Fragment

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The Key Ingredient: Unfoldings

An unfolding is a

representation of a net without

“merge” points

A complete prefix unfolding is

a finite initial part of the unfolding

that contains full information

about the reachable states

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Ordering Relations

■ Two transitions of an occurrence net are in one of the following relations:

□ A and B are in causal relation (A>B), iff there exists a path from A to B

□ A and B are in conflict (A#B), iff there are two transitions t1, t2 that share

an input place and there is a path from t1 to A and a path from t2 to B

□ A and B are in concurrency (A||B) relation iff A and B are neither in

causal, nor in conflict relation

A>C1

B>D2

B#A

A#D2

C2||D2

D2||C2

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FCB and Ordering Relations

Two process models are FCB-equivalent …

… if and only if, (complete prefix) unfoldings of both models expose

same ordering relations

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Structuring Process Models

Compute ordering relations

of the (unstructured)

process model

Construct a block-structured

process model from ordering

relations

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Ordering Relations Graph

An ordering relations graph

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Modular Decomposition Tree (MDT)

The MDT is unique and can be computed in linear time

The MDT

■ A linear (L) module is a total order on a set of nodes of a graph

■ A complete (C) module is a complete graph, or a clique

■ A primitive (P) module is neither trivial, nor linear, nor complete

A module is a set of edges with uniform structure

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Structuring Acyclic Process Models

A primitive module

Let G be an ordering relations graph. The MDT of G has no primitive module,

iff there exists a well-structured process model W such that G is the ordering

relations graph of W.

Heterogeneous Cyclic Rigid

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For further details…

Download and try:

• http://sep.cs.ut.ee/Main/bpstruct

• http://code.google.com/p/bpstruct/

Perspectives:

• Analyze

• Decompose (e.g. for distributed execution)

• Refactor (extract duplicate fragments into subprocesses)

• Visualize

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